The Australian Human Rights Commission says there is no evidence to support the Foreign Minister's claim that a large number of Iranian asylum seekers are economic migrants.

Foreign Minister Bob Carr says Australia needs a tougher assessment regime for asylum seekers to stem the growing number of what he describes as "economic migrants".

"What we've seen from the spike this year from Iran is that people are coming to Australia from majority religious and ethnic groups in their country, so persecution cannot easily be assumed," he said.

Senator Carr says there have "been some boats where 100 per cent of them have been people who are fleeing countries where... their motivation is altogether economic".

Prime Minister Kevin Rudd has also made comments asserting that many asylum seekers to Australia are not genuine refugees.

Yesterday, during his first media conference since his return to the leadership, Mr Rudd said a "whole bunch of people who seek to come to this country are economic migrants".

But the president of the Human Rights Commission, Professor Gillian Triggs, has told Lateline that 90 per cent of asylum seekers are found to be genuine refugees.

"When we were assessing asylum seeker claims up until August 13 last year, approximately 90 per cent of claims for refugee status were found to be valid," she said.

"They were assessed by the Australian processes genuinely to be refugees.

"Now that suggests that at least until the moment when the Government stopped assessing claims, the genuineness of the overwhelming majority of them was very clear on the evidence.

"So I think that Senator Carr is making an assumption for which there's no evidence."

Children in detention across Australia

Professor Triggs has also called for Australia to speed up the release of children and unaccompanied minors from detention centres.

She says this should be Immigration Minister Tony Burke's number one priority.

"I think it's very straightforward, it should be to release the children and in particularly unaccompanied minors into appropriate community detention, but get them out of the concrete camps and the wire," she said.

Professor Triggs says there are about 300 unaccompanied minors at Pontville. She says at least 26 of them have been in closed detention for eight or nine months.

"We are worried not only about those in Pontville. In total there are about 1,800 children in detention across Australia. Some of them in very isolated and bad conditions," she said.

The Government has progressively allowed more children and families to live in community-based accommodation while their claims are processed.

But Professor Triggs says the Government is not moving fast enough.

The Coalition's immigration spokesman, Scott Morrison, says he does not have faith that releasing children from detention will improve their conditions.

"Community detention is full. The Government is putting people back into alternative places of detention. It's not clear to me because of the appalling arrangements for bridging visas where children would potentially be more at risk."